How Often Do Triple-Digit Days Occur?

Posted June 28, 2009, 5:22 PM.

As summer ramps up in the inland valleys of Riverside and San Diego counties, the season of sweltering triple-digit heat waves is here again.

With a couple of hot days just recorded at the end of June, it's worth visiting just how often it gets hot.

Most 100°F days are recorded in the summer months of June, July, August and September, although in some circumstances they occur in April or May, or in October.

The hottest communities in the past five years were Lake Elsinore, Wildomar, Menifee, Perris and Hemet. All or part of each community is along the Elsinore convergence zone, where air from south and north mixes together, due to mountain topography.

The coolest communities are Fallbrook, De Luz, Temecula and Murrieta, in that order. All of those southern communities, particularly Fallbrook and De Luz, benefit from robust coastal breezes on most summer afternoons.

Records and averages since 2004 for WeatherCurrents stations are as follows: